The present invention deals with milling machines. More particularly, the present invention deals with a milling machine accessory providing both automatic and manual control for a quill of a milling machine.
Milling machines commonly used by operators for milling items, such as metal, take several forms. Typical milling machines are found in many tool rooms, mold shops, U.S. government facilities, and many other type of facilities. These common milling machines are manufactured by many companies worldwide. One commonly known milling machine is referred to as a knee mill. A typical knee mill has several major components. One component is a base portion which supports a knee, saddle and a table. The table is mounted on the saddle and the saddle is mounted on the knee. The workpiece rests on, or is fastened to the table during milling. The table is operable to move the workpiece along a first axis of movement generally adjacent the knee mill base.
The saddle is connected to the knee portion and supports the table. The saddle is operable to move the table, and consequently the workpiece, along a second axis of movement which is perpendicular to the first axis of movement. The second axis is defined along a line extending generally into and away from the milling machine. The first and second axes of movement are commonly referred to as the X and Y axes.
Another portion of a typical milling machine is referred to as a ram. The ram extends outwardly from the base portion and is used to support another major component of the milling machine, the head assembly.
The head assembly includes a spindle and a quill. The spindle holds a milling tool used for milling the workpiece. The head assembly also includes a spindle motor for causing the spindle to rotate within the quill. The quill is movable along a third axis of movement which is perpendicular to the first and second axes of movement. The third axis of movement is generally defined by a vertical line extending in both directions through the center of the spindle. The third axis is commonly referred to as the Z axis.
Prior milling machines have been operated in substantially three modes. The modes include manual operation, two axis operation and three axis operation.
In the manual mode, the milling machine is provided with manually operated devices to accomplish movement along the three axes of motion. In other words, the milling machine is provided with mechanical handles or cranks coupled to screws to move the appropriate portion of the milling machine along the corresponding axis of motion. The table is provided with a hand crank attached to a screw to move the table along the first axis of motion. Similarly, the saddle is provided with a handle connected to a screw to move the table along the second axis of motion. Also, the quill is coupled to a mechanical lever arm or handle which, when rotated, moves the quill up and down along the third axis of motion. In this way, the workpiece can be manually moved relative to the rotating spindle within the quill to an appropriate location for desired machining.
In order to manually position the workpiece with the hand cranks, the operator manually turns the X or Y crank to desirably position the workpiece with respect to the tool along two axes of movement. The operator tracks the movement via position indicating dials, electronic readouts, or other similar means.
Past milling machines have also been operated as two or three axis automatic machines. In two or three axes CNC milling machines, automatic positioning is provided along either two or three axes of motion. Machines which have been made to position the table and saddle automatically are referred to as two axis automatic machines. In two axis automatic machines, servo motors are coupled to the table and saddle screws for driving the table and saddle into position. The servo motors are coupled to a computer or other type of automatic motor controller. The computer receives position information from an operator, or from a stored program, and controls the servo motor to automatically position the machine along the axes of motion to a desired position based upon the position information received. In such a system, movement of the quill along the third axis, or z axis, is typically left to be manually operated.
In two axis milling machines, the table and saddle are automatically positioned using the computer controlled servo system discussed in the previous paragraph. In a three axis machine, however, movement of the quill along the third axis is also automated. This type of machine is referred to as a three axis Numerically Controlled (NC) or Computerized Numerically Controlled (CNC) milling machine.
Automation of the quill in three axis machines has typically taken one of three forms. First, a servo motor is attached to a ball screw which is, in turn, attached to an exposed portion of the quill on the head assembly. The servo motor controlled by the computer provides automatic positioning of the quill. However, connection of the ball screw to the quill substantially interferes with, or destroys, the ability of an operator to operate the quill manually.
In a second method of quill automation in three axis machines, a gear box is physically installed on the manual quill lever arm. A servo motor is coupled to drive the gear box to rotate the quill lever arm. The servo motor, in turn, is connected to a computer to provide automatic quill movement. However, having the gear box physically mounted to the quill handle also substantially interferes with, or destroys, the ability to manually operate the quill.
In a third method of quill automation in a three axis machine, a servo motor is coupled to a small hand crank on the head assembly which is, in turn, coupled to the quill. The servo motor is coupled to a computer to provide automatic quill positioning. This method also substantially interferes with, or destroys, the ability to provide manual operation of the quill.